In Dante's Inferno, by Dante Alighieri, why is the false counselors' punishment to be encased in a tongue of flame?

In Dante's Inferno (by Dante Alighieri), Dante is on his life's journey and realizes he has become lost. The Roman poet Virgil comes to the rescue (at the request of Beatrice) to help Dante continue his religious pilgrimage and find himself right with God; in order to finish his journey, however, he must travel through Hell.

In Dante's Inferno (by Dante Alighieri), Dante is on his life's journey and realizes he has become lost. The Roman poet Virgil comes to the rescue (at the request of Beatrice) to help Dante continue his religious pilgrimage and find himself right with God; in order to finish his journey, however, he must travel through Hell.

Dante and Virgil come to the eighth circle ("bolgia" or "ditch"), which addresses fraud (any kind of lying or misrepresentation).

Two further cantos are devoted to the fraudulent advisers or evil councillors, who are concealed within individual flames.

Included in these areas is anyone who not only lied or gave "false advice," but also anyone who consciously caused others to take part in fraudulent activities. This area punishes all kinds of deception. For instance...

That these particular kinds of sinners are doomed to suffer in a "tongue of flame" is tied directly to the punishment doled out to Guido I da Montefeltro. While serving Pope Boniface VIII, Guido directed the Pope to accept terms for surrender from the strong hold of the Colonna family in Palestrina. However, his deceit was great in that once the family had been given this "false amnesty," Guido also told the Pope to destroy the fortress and all inside. While Guido was forgiven by the Pope for his "evil advice," Dante explains that the Pope's absolution was worthless, for forgiveness can only be granted by a sinner's contrite heart: sorrow for one's sins and the pledge to do all one can to avoid repeating the offense again. Dante says that one cannot be forgiven as Guido allegedly was, before he committed the sinful act...and in light of the fact that after being absolved of the sin, he knowingly went ahead anyway.

Dante notes that Guido I da Montefeltro was punished for his sin of fraud in granting the Colonna family a false or insincere amnesty (terms of surrender). In Dante's Inferno, Guido is punished within the flame, as are others like him.

The specific punishment by fire is foretold in the Book of Revelation in the Bible's New Testament, Chapter 21, verse eight:

But the cowardly, the unbelieving, the vile, the murderers, the sexually immoral, those who practice magic arts, the idolaters and all liars--their place will be in the fiery lake of burning sulfur. This is the second death.

Not only will cowards, murderers, the sexually immoral, those who worship idols, and those who practice magic be thrown into a "fiery lake," but liars (frauds) will suffer there as well, based on this Biblical text.